pmkap,
this is an enthusiasm, which can be well explained - class D amp have no such bad sound as predicted, if they show shame specs even (e.g. zappuls have several percent THD in highs, and people likes it yet). Maybe not so much loop gain, or/and higher pole frequency vs typical class AB, maybe something else do the sound of class D amp better then their specs. About the specs.. no problem, by the huge loop gain or/and faster switching, which, of course, preferable - day by day faster&cheaper MOSFET's appears. Some time ago i've made UcD400 THD measurement, at the factory adjusted dead time the module gave .0175%@-3db(80W@8Ohm) with good efficiency. Decreasing dead time gave .005%@-3db, but pretty bad efficiency, i'm sure that newest MOSFET's, in this case, will help to avoid the losses, and keep performance same or better (loop gain around 30db, 35khz pole=flat THD/Freq plot in the audio band). BTW, that's excellent initial linearity, so amp without feedback would be have THD=.15%@80W!
Other excellent example is JohnW amp, i don't know how much feedback he has used, but the specs is the same or better vs best of the audio DAC chips.
this is an enthusiasm, which can be well explained - class D amp have no such bad sound as predicted, if they show shame specs even (e.g. zappuls have several percent THD in highs, and people likes it yet). Maybe not so much loop gain, or/and higher pole frequency vs typical class AB, maybe something else do the sound of class D amp better then their specs. About the specs.. no problem, by the huge loop gain or/and faster switching, which, of course, preferable - day by day faster&cheaper MOSFET's appears. Some time ago i've made UcD400 THD measurement, at the factory adjusted dead time the module gave .0175%@-3db(80W@8Ohm) with good efficiency. Decreasing dead time gave .005%@-3db, but pretty bad efficiency, i'm sure that newest MOSFET's, in this case, will help to avoid the losses, and keep performance same or better (loop gain around 30db, 35khz pole=flat THD/Freq plot in the audio band). BTW, that's excellent initial linearity, so amp without feedback would be have THD=.15%@80W!
Other excellent example is JohnW amp, i don't know how much feedback he has used, but the specs is the same or better vs best of the audio DAC chips.
Hi DJNUBZ: I forgot to mention a couple of other things about the Zappulse 700XE.
The THD, according to Lars and unlike the 2.3SE, is <0.02% across the audio range. This might mean that you do not have to be so fussy with the PS, although being fussy will not hurt.
The 2.3SE does have some EMI issues, but I do not know if the 700XE will have the same EMI issues? You will need to ask Lars about any EMI issues. Just be aware that he is somewhat slack at replying to emails?
If there is anything else I can think of, I will post it.
Hope this helps
The THD, according to Lars and unlike the 2.3SE, is <0.02% across the audio range. This might mean that you do not have to be so fussy with the PS, although being fussy will not hurt.
The 2.3SE does have some EMI issues, but I do not know if the 700XE will have the same EMI issues? You will need to ask Lars about any EMI issues. Just be aware that he is somewhat slack at replying to emails?
If there is anything else I can think of, I will post it.
Hope this helps
IVX,
The intent of my post was not to criticize switching amplifiers in comparison to other linear amps. I've heard well implemented amps based upon that same TA2024, and within its power constraints, have been very impressed. I've also heard UCD amps and have similarly been impressed. The choice at this point is not one of technical measurements, but rather one of subjective preferences based up details of implementation rather than constraints inherent in topologies.
My intent (using the exact words that Dmason started his post with, and ending with the same patronizing quote from Robert Burns) was to point out to him that he was guilty exactly the same transgression he accused mastertech of - not knowing what the heck he was talking about.
The intent of my post was not to criticize switching amplifiers in comparison to other linear amps. I've heard well implemented amps based upon that same TA2024, and within its power constraints, have been very impressed. I've also heard UCD amps and have similarly been impressed. The choice at this point is not one of technical measurements, but rather one of subjective preferences based up details of implementation rather than constraints inherent in topologies.
My intent (using the exact words that Dmason started his post with, and ending with the same patronizing quote from Robert Burns) was to point out to him that he was guilty exactly the same transgression he accused mastertech of - not knowing what the heck he was talking about.
Mosfets were the real barrier that put a cap on switching frequency that limited them to being for sub use only.
Also it seems not many knew how to make a good amp of it, but I'm sure had the right mosfet existed back then placed in the right hands... some amp would have rose above the rest.
Also it seems not many knew how to make a good amp of it, but I'm sure had the right mosfet existed back then placed in the right hands... some amp would have rose above the rest.
Just testing out some FX on my new soundcard. Under Vocal/Wide Enhancer I found preset #27 by the name of "Transistorized".
It has a veeery edgy, bright, gutted sound with ear bleed fake highs and zero bass, the "full feedback applied" sound.
Reminds me very much of a very cheap class A/B only with an unusual clarity. Scary.
It has a veeery edgy, bright, gutted sound with ear bleed fake highs and zero bass, the "full feedback applied" sound.
Reminds me very much of a very cheap class A/B only with an unusual clarity. Scary.
Déjà vu all over again
Ivan,
This is the sound card I am planning to use as well. I too will be tweaking it, replacing caps and op-amps, etc. I am also planning to use it for a listening reference and as a THD instrument. What software are you planning to use for this? I have no money to buy an expensive package so am looking for something to do the job that I can download. Do you know of anything available that actually works? Have you used a sound card this way before? If you have I would like to know what problems I can expect.
Thank you,
Roger
IVX said:
Ivan,
This is the sound card I am planning to use as well. I too will be tweaking it, replacing caps and op-amps, etc. I am also planning to use it for a listening reference and as a THD instrument. What software are you planning to use for this? I have no money to buy an expensive package so am looking for something to do the job that I can download. Do you know of anything available that actually works? Have you used a sound card this way before? If you have I would like to know what problems I can expect.
Thank you,
Roger
http://www.stereophile.com/amplificationreviews/805cia/ Sterophile review of a Class "D"
"D-100 uses about 80% of the UcD 180 circuit—we add the final 20% when we get our custom version of the board here."
"D-100 uses about 80% of the UcD 180 circuit—we add the final 20% when we get our custom version of the board here."
Roger,
You can try RMAA free soft, or something else 30 day trial, but much convenient. I see one problem with 1212..it's 10 times more expensive vs my previous audigy, which have .002% THD loopback, that is worse, but still well enough.
You can try RMAA free soft, or something else 30 day trial, but much convenient. I see one problem with 1212..it's 10 times more expensive vs my previous audigy, which have .002% THD loopback, that is worse, but still well enough.
overrating class d sq
I own both a Crown K1 and K2 and neither one comes at all close to the sonic accuracy or sound quality of my home brew DC coupled all triode OTL amplifier (which has a damping factor of over 100 out to 20khz, btw), and consistently sounds more incisive and musical with much more detailed imaging and far, far more consistent sound stage in every way than the class D amplifiers.
Not to say that Class D amps aren't best at what they do, which is high efficiency, but any decent tube amp matches Class D wrt low level linearity.
I own both a Crown K1 and K2 and neither one comes at all close to the sonic accuracy or sound quality of my home brew DC coupled all triode OTL amplifier (which has a damping factor of over 100 out to 20khz, btw), and consistently sounds more incisive and musical with much more detailed imaging and far, far more consistent sound stage in every way than the class D amplifiers.
Not to say that Class D amps aren't best at what they do, which is high efficiency, but any decent tube amp matches Class D wrt low level linearity.
The K1 and K2 are better sounding than many other SS amps and particularly good in the bass (the K2 is just the thing for my proposed HT subwoofer system using 16 long throw 12" drivers wired to 3 ohms/side to get all the class D bass goodness possible out of a 15A circuit)and I'm sure there's a number of better Class D implementations than them sonically nowadays that I haven't heard but it doesn't seem to me to be a case of having once heard Class D, never back to linear amplification.
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